Question

I have a tab bar app that works. Each tab is a UINavigationController whose root view is some kind of UIViewController, often a UITableViewController.

There are instances in the app where I want to display a full-screen “veil” with a message about what’s happening until some operation completes. The point is to swallow up any touches on the UI that would navigate away from where the operation started.

The veil is a UIView subclass. There is one singleton instance of the class. When displayed, I insert it as a subview of the UITabBarController view. The view appears over the entire UI, tab bar included. Great!

Here’s the problem. I can tap the tabs and the UI changes. What I would have expected is that my veil view would have just swallowed up the touches.

I have implemented in my veil class the various touches{Began|Ended|Moved|Canceled} methods (as do-nothing methods), but the touches are still picked up by the tab bar, and frankly by any object under whereever I happen to touch.

I’ve also tried overriding a number of other methods including nextResponder, hitTest:withEvent:, etc, to no avail.

I am a little stumped at this point. I’m hoping someone will have some sage advise. 🙂

Thanks.

Answer 1

It’s not safe to modify the view hierarchy of framework classes. You would be much better-served simply adding it as a subview of the window itself. As for consuming touches, if making this change doesn’t work, then you should also verify that userInteractionEnabled is set to YES on the view. You should not have to actually implement any touch-related methods.